Simulation and control of radiant floor cooling systems: Intermittent operation and weather-forecast-based predictive controls

There has been great interest in the radiant floor cooling system over the past decades due to its great potential for energy conservation and load shifting, and the improvement of indoor thermal comfort. However, as a thermally activated building system, its performance is highly related to the building enclosure thermal mass through heat exchange with the outdoor environment, and therefore, its operation is challenged by control strategies. Because of the shift characteristic of the cooling load during the day and variable weather conditions, realistic operation will increase the park load if neglecting the predictive scheme. This study proposes two control strategies, intermittent operation and weather-forecast-based predictive controls, which were applied and simulated in a real demonstration office building located in Jinan, China. Displacement ventilation (DV) was used to maintain the requirement of fresh air and shifting of peak load. The TRNSYS program was utilized for the analysis of energy saving potential and optimization of the control settings. The results show that weather-forecast-based predictive control can improve indoor comfort. Intermittent operation during the day had no significant effect on the indoor temperature fluctuation due to the response period, while it decreased energy use by 3.3% to 7.5% when the system was turned off in advance. In summary, the combination of intermittent operation and weather-forecast-based predictive controls can better guide the operation of radiant floor cooling systems and will reduce energy use in the building sector.